The polymerization of non-conjugated dienes to form polymers and copolymers that incorporate recurring units of cyclic moieties in the polymer or copolymer backbone is known. While it had been presumed that polymerization of non-conjugated dienes produces only cross-linked polymers, cyclopolymerization of diallyl quarternium salts to linear polymers was first reported by G. B. Butler in 1947 (J. Amer. Chem. Soc., 71, 3120). Since then, a large variety of non-conjugated dienes have been reported to undergo cyclopolymerization.
For symmetrical, non-conjugated dienes, it has been shown that all of the well-known methods of polymerization can be employed to initiate cyclopolymerization. Polymerization by free radical initiation, cationic and anionic initiation have been demonstrated. Cyclopolymerization of divinyl benzene has been accomplished using Ziegler-Natta catalysis.
Copolymerization of non-conjugated dienes with vinyl monomers is also known (G. B. Butler, et al., J. Poly. Sci. 48, 279 (1960). Depending upon the comonomer pair and the copolymerization conditions, the product copolymer may contain recurring units of ring moieties plus vinyl moiety or the vinyl and diene moiety may combine to form a common recurring ring moiety.
Additional examples of cyclopolymerization are abundant in the chemical literature. The technology is summarized in the Encyclopedia of Polymer Science and Engineering, Vol. 4, 1986, pp 543-598.
Recently, a novel catalyst system has been reported which has been found to be particularly effective for the polymerization and copolymerization of 1-alkenes. In U. S. Pat. Nos. 4,827,064 and 4,827,073 to M. Wu, incorporated herein by reference, the unique catalyst system is reported. The catalyst is used for the preparation of superior hydrocarbon lubricants having low methyl to methylene branch ratio by oligomerization of alpha olefins. The catalyst comprises reduced valence state Group VIB metal oxide catalyst on porous support. The specific method for lubricant preparation employs as catalyst an activated chromium catalyst comprising carbon monoxide reduced chromium on a silica support. The novel lubricant compositions which can be produced by activated chromium on silica catalysis comprise polyalpha-olefins polymers and/or copolymers.
Although the versatility and effectiveness of activated chromium on silica catalysis for 1-alkene polymerization and benzene alkylation has been well documented, little has been known relative to the reactivity of the catalyst with polyenes, particularly non-conjugated dienes. Despite the abundance of research conducted on cyclopolymerization, activated chromium on silica catalyst has not been reported in the prior art as a catalyst for aliphatic non-conjugated diene cyclopolymerization. Indeed, the uniqueness of the activated chromium catalyst has tended to inhibit those skilled in its use to conclude how it would function in diene polymerization compared to known cyclopolymerization catalysts. Accordingly, the fact, as presented herein, of the activity of reduced chromium on silica catalyst in non-conjugated diene polymerization represents a distinctly unanticipated discovery.
It is an objective of the present invention to provide novel polymer and copolymer compositions comprising atactic polymeric aliphatic hydrocarbon compositions comprising randomly recurring 1-methylene 3-cycloalkyl units.
It is a further object of the present invention to provide a method for the production of the foregoing compositions employing as catalyst reduced chromium on silica for non-conjugated diene polymerization.
Another objective of the present invention is to provide the foregoing compositions in a manner and form compatible with their use as lubricants or lubricant additives.